The advantage to doing CPL in a multi engine is that a multiengine time looks better than single engine time. Same as jet engine time looks better than piston time. If you can afford it, the more multi time, the better.
The disadvantage is that multiengine time costs more. Most people try to balance multi time vs. cost.
Only note worthy if you get lots of it, a recruiter wont care if you've got 10, 15, or 20 hours more than another candidate, you would make up any "deficit" within a few days of line flying!
What it will do though is give YOU some extra hours in the aircraft which could make the IR a fraction easier.
I left BCFT after groundschool as I didn't like the look of their flying, plenty of people stayed on and enjoyed it and got good results, it comes down to personal opinion and a visit is a must. Make sure you visit a few schools to help you compare apples with apples.